Justify, how far?
On the axis: Relation to certainty · the chain of reasons
Every reason rests on another reason: does the chain stop at a foundation, turn in a circle, or run off to infinity? This is the skeptic's lever.
Justification
The skeptic observes that to every assertion an assertion of equal strength can be opposed: this is the (isostheneia) of contrary reasons. Having no means to decide, he (epoche), not by choice but because the unresolved conflict compels him to. Sextus systematizes this mechanism in the inherited from and , which drive every claim to knowledge toward infinite regress, circularity, or an arbitrary stopping point. Where would make doubt a stage toward a foundation, Sextus makes it a dwelling: no definitive certainty is attainable, and the skeptic carries caution so far as not even to assert dogmatically that there is no certainty.
To every argument an equal argument is opposed.Outlines of Pyrrhonism, I, 12
Outlines of Pyrrhonism, I, 8 and 12 · Outlines of Pyrrhonism, I, 164-169 (the five modes of Agrippa)
Anchors: Sextus Empiricus
leads to: Justification of belief (The chain of reasons)